He's a playboy who comes from a wealthy family who own a series of hotel chains. He more often goes for older and sometimes married women.
Ranmaru is incredibly handsome and charming, so he has many ladies swooning over his every step. However he prefers older wealthy women that could pass for their early twenties and because of this, he often has get invited to luxury places his current girlfriend owns. Often when he mentions his girlfriend, its always different from the last, but he acts the same as he always does with each one.
Surprisingly, Ranmaru is the most mature of the guys and often is the one to pick up the phone when Mine calls to threaten them about a time limit and rent. When he's talking to her, he makes sure to flirt to hopefully make her change her mind, but with the amount of men she's been with she's knows every trick in the book and can see right through him.